It's not necessary to patch the few remaining glitches. BXR can be annoying but people don't do it all the time and you can adjust your play style for it. Super-bouncing was almost gone in H2 Vista, most likely it'll be the same in TMCC. Getting out of the map is either harmless, on Gemini it does you no good for example, or it's just not done by that many people. Most of the time when people try to set it up they just get killed with the objective.

Everything, all the other game breaking bugs with Halo 2 had been pretty much patched by the time the 1.5 update came around. That along with the dedicated servers pretty much mitigates almost all of the issues to the point where it's really become and non-issue. It's not worth the time they would need and the fact that it would take away something people expect which is relatively harmless.